''Sent later'' does not work (does not sent at all, or sent as soon as I start my computer)

”Sent later” does not work (does not sent at all, or sent as soon as I start my computer). I already sent a message about this, got a replay with some questions but then no answer. I would like to get in contact a.s.a.p with someone from mailbutler, otherwise I will cancel my subscription since I only use it for the ”sent later” option. I’ve been paying for something that does not work.